Tony Hambric Posted November 10, 2008 Share Posted November 10, 2008 The fuel pump on my 1977 280Z does not work. I removed the fuel pump and did a bench test, and the pump worked. I performed a voltage test on the wiring harness going to the pump, however with the key in the start position, I did not have power at the pump. I have yet found the fuel pump relay so that I can check it out. Any advice welcome! Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted November 10, 2008 Share Posted November 10, 2008 Just run a straight power source to it with a switch in the cabin. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted November 10, 2008 Share Posted November 10, 2008 the relay is under the passenger seat Quote Link to comment Share on other sites More sharing options...
Silver Mine Motors Posted November 10, 2008 Share Posted November 10, 2008 there are two wires going to your pump (ground and positive). the positive only turns on when you are cranking the motor. so that means the wire will not have power even if the key is on the "on" position. get somone to crank the car while your under it testing the positive wire. then you will know if it is not working. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted November 10, 2008 Share Posted November 10, 2008 Power is only supplyed to the fuel pump when the key is in the start position (while it's cranking) and then once it's running, there is a switch in the AFM that supplys voltage. This is by design so the fuel pump will quit if the engine stalls. (such as in a wreck) so the thing doesn't sit there pumping fuel all over a hot engine. Some later models also have a low oil pressure cut off switch. There are a couple relays involved and running the prolem down will take a little effort and some skill with a meter and detective work. But whatever you do... don't do this Just run a straight power source to it with a switch in the cabin. The system is design this way on purpose and for saftey. You should be able to put the key in the run position while the engine isn't running and pop the boot off between the air filter and AFM and stick your little fingers in there and raise the flap off it's stop and hear the fuel pump kick on. Parts america has the wiring diagram posted online, do a little searching and you'll find a link (sorry to lazy to do it for you) and check the system. Follow the wiring along, some of it runs along the floor and can get crusty. Make sure the wiring diagram is the right one for your car. They changed it up between years in 76 - 78 Quote Link to comment Share on other sites More sharing options...
Tony Hambric Posted November 11, 2008 Author Share Posted November 11, 2008 Power is only supplyed to the fuel pump when the key is in the start position (while it's cranking) and then once it's running, there is a switch in the AFM that supplys voltage. This is by design so the fuel pump will quit if the engine stalls. (such as in a wreck) so the thing doesn't sit there pumping fuel all over a hot engine. Some later models also have a low oil pressure cut off switch. There are a couple relays involved and running the prolem down will take a little effort and some skill with a meter and detective work. But whatever you do... don't do this The system is design this way on purpose and for saftey. You should be able to put the key in the run position while the engine isn't running and pop the boot off between the air filter and AFM and stick your little fingers in there and raise the flap off it's stop and hear the fuel pump kick on. Parts america has the wiring diagram posted online, do a little searching and you'll find a link (sorry to lazy to do it for you) and check the system. Follow the wiring along, some of it runs along the floor and can get crusty. Make sure the wiring diagram is the right one for your car. They changed it up between years in 76 - 78 I had a brain cramp! What does AFM stand for? I know it's location, however can't recall the name. Quote Link to comment Share on other sites More sharing options...
woldson Posted November 11, 2008 Share Posted November 11, 2008 Air flow meter. Trap door thingy before thottle body. Quote Link to comment Share on other sites More sharing options...
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